Air brake



Patented May 2, 1939 2,156,726

UNITED STATES PATENT OFFICE AIR BRAKE Charles A. Campbell, Watertown, N.Y., assignor to The New York Air Brake Company, a corporation of NewJersey Application May 24, 1938', Serial No. 209,793

'7 Claims. (01. 303-36) This invention relates to air brakes andparblanks the port 2| so that the charging rate is ticularly to triplevalves. The object of the inreduced to the capacity of the smaller port22. vention is to provide a comparatively simple form The stem of thepiston houses at its opposite of triple valve having desirable operatingcharends two opposed spring plungers. One of these,

5 acteristics both as to a preliminary service lap 24, is guided in achamber formed in what might movement and as to release-insuring andslide be described as the hub of piston M. It is urged valve unloadingfunctions. inward, that is away from the brake pipe side Anothervaluable feature is the use of a spring of the piston M, by a coilcompression spring 25. stop, which is provided primarily to control theThe spring is held under proper initial stress by release-insuringfunction, as a retard stop to a combined plug and spring seat 26threaded into 10 resist motion from normal release to restricted thecenter of the P S Movement of the release position, plunger 2d under theurge of the spring 25 is While the invention is capable of embodimentlimited by the f and W st t in more complicated forms of triple valve,for face the forward end of the plunger Z l stands example in theservice portion of the AB valve, n advance of the shoulder 28 formed onthe 16 it will be described as embodied in a relatively lower p on O t pston hub.

simple triple valve so that only essential func- Other plunger 9, ountedin the end of tions, particularly those relating to the invention theStem I5, is urged toward the pisto by Coil here under consideration,need be discussed. compr s n spr n 3| which is r n y m In th drawings;bined plug and spring seat 32 threaded into the 20 Figure 1 shows atriple valve embodying the end of the piston rod l5. The motion of theinvention in axial section, and includes the con- Plunger 29 Under theurge O Spring 3| is l ted nections to the auxiliary reservoir brake pipey the face 33 and in this p s t e end Of and brake cylinder. The valveis shown in replunger 29 Sta s in advance of the shoulder 34 2 lease andnormal recharge position formed on the lower portion of stem I5.

Fig, 2 is a fragmentary iew of the triple Mounted in a. notch in thestem l5, near itS valve in release and restricted recharge position.mid-length 50 as to have no pp c b 10st 111 Fig. 3 is a similar view ofthe valve in service tiOIl relatively to the is the graduating o iti n,valve 3-5 which is urged by a bow spring 36 into Fig. 4 is a similarView of the valve in prelimiseating engagement With the p f th a 9 narylap position; and slide valve 81. This main slide valve works on Fig. 5is a similar view of the valve in releasea ported Seat inthe bushing TheSlide Valve insuring position. is formed with upwardly extending wingsto In the drawings 6 represents a pipe bracket carry the bow spring 39which holds it to its seat.

t hi h are connected th brake pipe i an The main slide valve is capableof lost motion 85 auxiliary reservoir 8 and the brake cylinder 9 asrelatively to the p o 54 and ts Stem l5. clearly indicated in thedrawings. This lost motion is positively limited by the tt d t pipebracket 6 is t body ll of shoulders 28 .and 34 hereinbefore mentioned.th triple valve, and t i houses a cylinder t It is more closely limitedin each direction by the 40, cylinder bushing |2 and valve chamber tplungers 24 and 29 when these are seated against 40 a valve chamberbushing l3. Working in the the faces 27 d If the springs reactin bushingI2 is a triple piston hi whose stem l5 against l ne r 24 and 2 re v rp wed, th extends into the valve chamber and is guided at full lost motioncan occur. The parts are so diits inner end by a flange it which slidesin the mensioned that when the slide valve moves to 4' cup-shaped capl1. eitherrelease position (Fig. 1 or 2) its inward The piston M in thenormal recharge position ot o s ted by t e end 38 of the cap of Fig. lexposes a charging port l8. This leads member IT. to a passage l9 whichcommunicates with two The connection of the auxiliary reservoir to ports2i and 22 which, in normal recharge posithe slide valve chamber has beenexplained. The tion, communicate with the space to the right of brake pp is connected by the p s 4! t0 the 50 the piston l4 and consequentlywith the slide space 42 on the outer side of the triple piston I l.valve chamber, and with the auxiliary reservoir The brake cylinder port43 in the seat of slide 8, connected to the slide valve chamber by wayvalve 31 is connected to the brake cylinder by a of the passage 23. Whenthe piston moves into pipe 44. The exhaust port 45 in the slide valverestricted recharge position (Fig. 2) the piston seat has a branch 46also terminating in the slide 55 valve seat, and these ports communicateto atmosphere through a flow restricting choke 41, whose purpose will behereinafter more fully explained.

The slide valve 31 has a cavity 48 which connects the ports 43 and 45 inthe release position. It should be observed that since the end 38 of thecap I! determines release position, the position of the slide valve 31is the same in both Figs. 1 and 2.

There are two passages extending from top to bottom of slide valve 31,both of which are controlled by the graduating valve 35. The first ofthese is the service port 49. This port is blanked at the slide valveseat in release position, and registers with the brake cylinder port 43in service, preliminary lap and release-insuring positions (Figs. 3, 4and 5). The second through port is the release-insuring port 5| which isblanked at the slide valve seat in both release positions (Figs. 1 and2) and which registers with the extension exhaust port 46 in service,preliminary lap and release-insuring positions (Figs. 3, 4 and 5).

As stated, the upper ends of these two ports 49 and 5| are controlled bythe graduating valve 35. In release and normal recharge position(Fig. 1) the graduating valve blanks both ports, but this is withoutfunctional significance because both ports are then blanked at the seatof the main slide valve. In release and restricted recharge position(Fig. 2), these ports are also blanked at the slide valve seat, so thefact that the graduating valve exposes the upper end of port 5| in thislast-named position is also without functional significance.

In service position (Fig. 3) the graduating valve exposes the serviceport 49 which then registers with the brake cylinder seat port 43, so

mthat auxiliary reservoir air flows through the ports 49 and 43 to thebrake cylinder.

In Fig. 4, which is a preliminary service lap position, the graduatingvalve 35 is shown as closing the port 5| and just lapping the port 49 5so that the graduating valve has just lapped service flow.

In the release-insuring position of Fig. 5, the graduating valve lapsthe service port 49 and fully exposes the release-insuring port 5| whichis then in communication with the branch exhaust port 46, so that air isvented from the slide valve chamber to atmosphere but at a rate limitedby the choke 41.

The openings 52, 53 are provided to vent the space to the right of theflange I6 so that it will not exercise a compression or piston action inthe cap IT,

The operation can now be explained.

Operation In initial charging, air from the brake pipe 1 flows from thechamber 42 through the port I8 and thence in parallel through the ports2| and 22 to the slide valve chamber.

In release and normal recharge position the slide valve has been movedto the right until arrested by the end 38 of the cap H. The exhaustcavity 48 connects the brake cylinder port 43 with th exhaust port 45 sothat the brake cylinder is connected to atmosphere. The spring 25 is notcompressed and it will be observed that the plunger 24 and spring 25serve as a retard stop to arrest the piston M in normal chargingposition.

During release the triple valves on the cars in the forward portion ofthe train will be moved by the rapid rise of brake pipe pressure torestricted recharge position (Fig. 2). As shown in Fig. 1 the slidevalve 31 is arrested by the end 38 and the cap l1, and hence can move nofarther to the right. Thus, if brake pipe pressure rises sharply, as itdoes at the forward end of the train, the piston moves inwardoverpowering spring 25 by reaction of the slide valve 31 againstthe'plunger 24. When the sharp rise of brake pipe pressure fades out thespring will restore the triple piston and the graduating valve to thenormal position of Fig. 1. Although the graduating valve then exposesthe release-insuring port 5| in Fig. 2, no flow occurs since the port 5|is blanked.

In response to reduction of brake pipe pressure, the triple piston ismoved out by dominant auxiliary reservoir pressure, the plunger 29engages the slide valve 31 and overpowers the spring 3| until shoulder34 on the stem engages the slide valve, then the slide valve and thepiston stem l5 move as a unit until the service port 49 registers withthe brake cylinder port 43. This connects the auxiliary reservoir withthe brake cylinder and this connection will be maintained untilauxiliary reservoir pressure falls nearly to equalization of brake pipepressure, at which time the spring 3| will assist in shifting the piston4 and graduating valve 35 to preliminary lap position (Fig. 4).

In this preliminary lap position the port 49 is just closed by thegraduating valve, and the action of spring 3| has been terminatedbecause plunger 29 is against face 33 and can move no farther.Subsequent brake pipe pressure reductions entail compression of thespring 3| to permit the graduating valve to expose the service port.

In the releasing movement, the triple piston I4 and graduating valve 35will move inward inde pendently of the slide valve, at least untilplunger 24 engages the slide valve. If the slide valve then sticks, asit may do, the piston will continue its inward motion overpoweringspring 25 until shoulder 28 on the valve approaches contact with theslide valve. At such time the release-insuring port 5| connects theslide valve chamber with the branch exhaust port 46 and also with theexhaust cavity 48. Choke 41 limits the flow rate to atmosphere and sincethe cavity 48 has considerable area the slide valve 31 is partlyunloaded so that its frictional resistance to motion is reduced just asslide valve chamber pressure is reduced. The effect of these two actionsis to insure prompt movement of the triple piston l4 and slide valve 31to release and recharge position (Fig. 1).

rom the construction above described it is obvious that this plunger 29with its spring assists graduation and particularly lapping motion. Theplunger 24 with its spring 25 not only serves as a retard stop in themotion between normal and restricted recharge position, but alsocontrols the action of the graduating valve in opening therelease-insuring port. The release-insuring action involves not merelythe venting of the slide valve chamber, but in addition thereto invalvesthe reduction of the loading differential on the slide valve and theconsequent relief of frictional resistance between the slide valve andits seat.

While one embodiment has been described in considerable detail, theinvention is not limited to this particular construction which isintended as exemplary.

What is claimed is:

1. A brake controlling valve device for automatic brakes, comprising incombination a body adapted for connection with brake pipe, brakecylinder and auxiliary reservoir; a piston responsive to pressuredifferentials between brake pipe and auxiliary reservoir; a slide valvemounted on a seat in the body and shiftable thereon by the piston buthaving lost motion relatively to the piston; a graduating valveshiftable by the piston relatively to the slide valve; and yieldingmeans resisting relative motion of the piston and slide valve through atleast the terminal portions of the lost motion in each direction, theslide valve seat having a brake cylinder port and an exhaust port andthe slide valve having an application port and a release-insuring portwhich respectively register with said brake cylinder port and theexhaust port in application position of the slide valve, said slidevalve ports being lapped by the graduating valve when in itsmid-position, and opened selectively upon the overpowering of saidyielding means in opposite directions.

2. A brake controlling valve device for automatic brakes, comprising incombination a body adapted for connection with brake pipe, brakecylinder and auxiliary reservoir; a piston responsive to pressuredifferentials between brake pipe and auxiliary reservoir, said pistoncontrolling charging flow from the brake pipe to the auxiliary reservoirand having a normal charging position and an inner charging position inwhich the charging flow is restricted; a slide valve mounted on a seatin the body and shiftable thereon by the piston but having lost motionrelatively to the piston; means for arresting said slide valve inrelease position; a graduating valve shiftable by the piston relativelyto the slide valve; and yielding means resisting relative motion of thepiston and slide valve through at least the terminal portions of thelost motion in each direction, the slide valve seat having a brakecylinder port and an exhaust port and the slide valve having anapplication port and a releaseinsuring port which respectively registerwith said brake cylinder port and the exhaust port in applicationposition of the slide valve, said slide valve ports being lapped by thegraduating valve when in its mid-position, and opened selectively uponthe overpowering of said yielding means in opposite directions, saidyielding means serving to resist motion of said piston to the chargerestricting position when the slide valve is arrested in releaseposition.

3. The combination defined in claim 1, in which .the yielding meanscomprises a pair of springurged plungers mounted in the piston stem inopposed relation to each other and each limited in its motion toward theother so that the slide valve has an intermediate range of free lostmotion relative to the piston, and a further limited range of lostmotion against spring resistance in each direction.

4. The combination defined in claim 2, in which the yielding meanscomprises a pair of springurged plungers mounted in the piston stem inopposed relation to each other and each limited in its motion toward theother so that the slide valve has an intermediate range of free lostmotion relative to the piston, and a further limited range of lostmotion against spring resistance in each direction,

5. The combination defined in claim 1, in which the exhaust port in theseat communicates with a cavity in the seated face of the slide valvewhen the latter is in its application position and is restricted beyondsuch communication, whereby in its application position the slide valveis partially unloaded when the graduating valve exposes saidrelease-insuring port.

6. The combination of a brake controlling valve device, including apiston and a slide valve shiftable thereby, and includingrelease-insuring means rendered effective by releasing motion of thepiston relatively to the slide valve, to vent pressure fluid from thespace above the slide valve; of means for restricting such venting flowand causing back pressure developed by such restriction to react on theseated face of the slide valve to unload the same at least partially,whereby the releasing movement of the slide valve is facilitated.

'7. The combination with a triple valve, including a piston and a slidevalve actuated by said piston and mounted in a chamber subject to fluidpressure; of release-insuring valve means, rendered efiective by thesticking of the slide valve during releasing functions, to vent pressurefluid from said valve chamber; and means for developing back pressure inthe vented fluid and causing said back pressure to react upon the seatedface of the valve to unload the same.

CHARLES A. CAMPBELL.

